1. Field of the Invention
The present invention relates to a method and an apparatus for measuring a delay time. More particularly, the present invention relates to a method and an apparatus for measuring a delay time caused by crosstalk.
2. Description of Related Art
As the process of semiconductor integrated circuits (IC) progressively advances, the integration of the IC is increased and correspondingly the line width of the IC reduces. Therefore, the influence caused by the interference or the crosstalk in the connecting lines of the IC get more and more obvious with the increasing integration of the IC. In general, the crosstalk in the IC is usually caused by inductance or capacitance between two adjacent conductors, conductive layers, conducting wires, transmission lines, or connecting lines. In the IC, when a signal or energy is transmitted on a transmission line, the energy may influence another adjacent transmission line by coupling to the adjacent transmission line via the mutual inductance or the mutual capacitance between the two transmission lines. Conventionally, the crosstalk may be classified into near end crosstalk and far end crosstalk according to the distance between the two transmission lines. Particularly, when the density or length of the wiring of the layout of the IC increases, the influence of the crosstalk may be more obvious. For example, the crosstalk phenomenon of a connect line or bus line with a long length is generally serious.
In the IC, when a signal is transmitted on a transmission line, and a crosstalk phenomenon is generated between the transmission line and another adjacent transmission line, the transmission time of the signal may be influenced by the crosstalk, i.e., the transmission of the signal may be delayed by a delay time. At this moment, the delay time may influence the timing of the signals of the IC and generates an error, or even may result in some error of the timing, operation or function of the IC. Thus, the performance or the reliability of the IC may be adversely influenced, or sometimes may even lead to IC failure. Therefore, a crosstalk measuring method or a measuring device for effectively measuring or detecting the influence of the crosstalk, for example, for measuring the delay time, is very important.